Check valve for oxygen service



FIG. 1 is a perspective view of a check valve for oxygen service;

FIG. 2 is front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a top view thereof, of which a bottom view is a mirror image; and,

FIG. 5 is a right side view, of which a left side view is a mirror image.

The broken line showing is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a check valve for oxygen service, as shown and described. 